This invention relates to a combustion instability device and particularly for the reduction of instability which may develop in the combustion chamber of a rocket engine or jet engine. Screech liners eliminate combustion instability by absorbing some of the pressure pulsations that strike them, instead of reflecting it, and dissipate absorbed energy in the form of turbulence, eventually heat. In normal screech liner design practice, a liner containing apertures is separated from a solid backing wall by a backing volume. This type of construction is shown in U.S. Pat. No. 2,930,195 and U.S. Pat. No. 2,941,356. Other combustion instability reduction devices are shown in U.S. Pat. No. 3,483,698, U.S. Pat. No. 3,426,409 and U.S. Pat. No. 3,359,737. These last three patents involve the specific construction of the apertures.